Physics CH. 4 Quiz / Test: Motion and Force: Dynamics

Newton's First Law of Motion

An object in motion will stay in motion, and an object at rest will stay at rest, unless acted upon by an outside force

A push / pull / kick, something somebody does to an object

Applied Force. FA / FP

Aristotle v. Galileo and Newton on this first law of motion?

Aristotle said an object at motion wants to come to rest, and Galileo and Newton said an object in motion wants to stay in motion

How did Aristotle and Newton answer, "When an object is in motion, it its natural state rest? In other words, is it always 'trying' to stop?"

Aristotle said yes. Newton disagreed, and said an object in motion will always stay in motion unless acted upon by an outside force

When an object is in motion (or resisting motion) on a surface or through a viscous medium, there will be a resistance to the motion. What is this resistance called?

Friction

What is a resistance to changes in motion?

Inertia

What is the force that impedes motion when an object is actually moving

Kinetic friction

What is the measure of the inertia of a body?

Mass

You are driving your cute red sports car and rear end a semi-truck. The greater impact force (in magnitude) acts on.. Your car The truck Neither, same on both Not enough information to tell

Neither, same on both.

Who is the father of physics?

Newton

Force is measured in..

Newtons

Was Newton's work accepted?

No, because he was weird and into turning things into gold (alchemy)

An upward force on an object by a surface that the object is on, always perpendicular from the surface.

Normal Force. FN.

Which is generally larger, the force of static friction or the force of kinetic friction?

Static

What is the force that counteracts an applied force and keeps an object from moving?

Static Friction

Socially, what was Newton like?

Struggled with basic social cues and was maybe on the autism spectrum

Who has the larger acceleration?

The car, because when force is equal, the lesser mass must have the larger acceleration

How do area and friction relate?

They are nearly independent of one another

How did Galileo answer the question, "Which will fall faster, heavier or lighter objects?"

They fall at the same rate

The value of static friction changes as the

applied force changes

Mass is a property of the _____ itself.

body (unlike weight)

What describes the relationship between the motion of objects in our everyday world and the forces acting on them?

classical mechanics

An object either at rest or moving with a constant velocity is said to be in..

equilibrium

Newton was the first person to come up with a _____ force.

field

Newton knew there were forces present without...

motion

The direction of frictional force is _______ the direction of motion

opposite

You are babysitting tomorrow because it is a snow day and you need money!! The little girl you babysit wants to take a ride on a sled. Assuming you are on flat ground, should you push her or pull her? Why?

pull her

What is friction proportional to?

the normal force

The magnitude of the gravitational force acting on an object of mass m near the Earth's surface is called the ______ of the object

weight

When an object is in equilibrium, the net force acting on the object is..

zero, since the acceleration is zero

What is the coefficient of friction? What does it depend on?

µ Depends on the surfaces in contact

Fk =

µk Fn

Newton's Third Law of Motion?

For every action force there is an equal and opposite reaction force.

What is the interaction between two or more objects which uses energy and impacts motion?

Force

What is the action force and reaction force, always acting on two different objects?

Force Pairs

Whenever two surfaces are in contact. A force that always opposes motion.

Force of Friction. Ffr.

Force of the Earth pulling down on an object. Present in every single situation.

Force of Gravity. mg.

Present anytime there are ropes or strings pulling on an object.

Force of Tension. FT.

Explain balanced v. unbalanced forces.

- Forces acting on a single object add up to zero - Forces acting on a single object do not add up to zero, and the object accelerates

What are some examples of how Newton's first law can be applied to our everyday lives?

- seatbelts - airbags - washing machines - the monkey gun - the famous tablecloth demo

Your best friend is an alien (sorry you have no friends on Earth ) and calls you from the Moon to tell you that she has just won one Newton of gold in a radio contest. Excitedly, you tell her that you entered Earth's version of the same contest and you also won one Newton of gold. Who won the prize of greatest value, or are they equal?

1 N = mg m = 1 N / g The alien got the better deal because g is smaller on the moon

What are the 3 things force can do?

1. Can stop something from moving / keep something 2. Can start motion 3. Can change something's motion while it is moving

What two factors affect how easy it is to stop it?

1. speed 2. mass

Name the 4 types of fundamental forces in decreasing strength?

1. strong nuclear force 2. electromagnetic force 3. weak nuclear force 4. gravity (weakest, but over a far range)

What are the 2 conditions under which classical mechanics does not apply?

1. very tiny objects that use quantum mechanics 2. objects moving near speed of light or objects that are massive like planets

Explain the difference between Contact and Field forces?

Contact: When two objects are in physical contact with each other Friction, pushing or pulling, kicking, Field: A force between two objects when they are not touching. "acts at a distance" Magnets, Gravity

Newton's Second Law of Motion?

Exploring force, mass, and acceleration sum of all forces = ma

What is the force that balances the force of gravity when an object is at rest on a surface?

FN.